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Purpose: A new protective method against the spinal cord ischemia that occurs during aortic clamping was investigated in dogs. Oxygenated blood containing prostaglandin E"1 (PGE"1) was administered at the clamped aortic segment, and the effect was evaluated by measurement of the sensory evoked spinal potential (SESP). Methods: In 30 dogs, a thoracotomy was made with dissection of the thoracic aorta. After intravenous heparin (100 units/kg) was administered, the proximal and distal descending thoracic aortas were cross-clamped for 60 minutes. Group A (n = 10) received oxygenated blood at the rate of 1.0 ml/kg/min. Groups B (n = 10) and C (n = 10) received oxygenated blood at the same rate, with PGE"1 at the dosage of 25 and 50 ng/kg/min, respectively. The infusion was continuously administered throughout the entire period of ischemia. SESP was measured with epidural electrodes before clamping, 10 and 60 minutes after clamping, and 10 and 60 minutes after declamping. Neurologic outcome was assessed at 24 hours after the operation and graded according to the method of Tarlov. Results: There was no significant hemodynamic change in any group. At 60 minutes after clamping and at 10 and 60 minutes after declamping, the amplitude of SESP was lower than that at preclamping in groups A and B (p < 0.05). At 60 minutes after clamping and at 10 and 60 minutes after declamping, the SESP was more markedly decreased in group A compared with groups B and C. Regarding postoperative neurologic outcome, the dogs with SESP amplitude of more than 50% of the preclamping control value at 60 minutes after clamping showed neither paralysis nor paraplegia. Seven of nine dogs with less than 50% SESP amplitude showed neurogenic deficit. In a comparison of groups A, B, and C, the Tarlov score for group A dogs was significantly lower than that for group C dogs (p < 0.05). Conclusion: In this model, PGE"1 administration at the rate of 50 ng/kg/min showed sufficient spinal cord protection against ischemia without a decrease in the blood pressure. Further studies are needed to determine the dose that will provide the maximal protective effect and to determine the maximum duration of ischemia against which PGE"1 shows protective effects. (J Vasc Surg 1998;28:301-7.)

Grafting an internal thoracic artery to a coronary artery with moderate stenosis remains controversial. Competitive flow from the native coronary artery has been proposed as the cause of distal narrowing and ultimate failure of the internal thoracic artery graft. We investigated intraoperative phasic blood flow in internal thoracic arteries grafted to coronary arteries with various degrees of stenosis and the influence of stenosis on postoperative angiographic findings. One hundred patients who underwent coronary artery bypass grafting of an internal thoracic artery to the left anterior descending coronary artery were divided into three groups according to degree of coronary stenosis. Group 1 included 39 patients who had 75% or less stenosis, group 2 included 34 patients with stenosis from 76% to 90%, and group 3 included 27 patients with stenosis greater than 90%. Mean flow and peak systolic flow of internal thoracic artery graft in group 1 were lower than those in group 2 ( p < 0.01, p < 0.05). Peak diastolic flow in group 1 showed no difference from flows in groups 2 and 3. In eight patients in group 1, internal thoracic artery flow showed a predominant diastolic peak with characteristic systolic reversal as a result of competitive flow from the native coronary artery. Angiography at 1 month showed that the internal thoracic artery graft was patent in every case. Relative contributions of native coronary artery and internal thoracic artery flow to distal perfusion differed among the three groups ( p < 0.001). In group 1, 15% of patients showed native-dominant flow, 62% showed balanced flow, and 23% showed internal thoracic artery-dependent flow. In group 2, 9% of patients showed native-dominant flow, 29% showed balanced flow, and 62% showed internal thoracic artery-dependent flow. In group 3, 96% of patients showed internal thoracic artery-dependent flow. String sign of the internal thoracic artery graft developed in only three patients; in two of these patients internal thoracic arteries were grafted to coronary arteries with stenosis of 50% or less and in the other patient there was competitive flow from a diagonal vein graft. Eleven of 13 internal thoracic arteries grafted to coronary arteries with stenosis of 50% or less did not show string sign. Competitive flow from a moderately stenotic coronary artery did not predispose the patient toward string sign of the internal thoracic artery graft in the presence of substantial diastolic internal thoracic artery flow. We conclude that internal thoracic artery grafting is acceptable for a moderately stenotic coronary artery. (J Thorac Cardiovasc Surg 1996;112:253-9)

Familial hypercholesterolemia is an autosomal dominant disorder caused by a mutation of the gene for the low-density lipoprotein receptor and is characterized by rapidly progressing coronary atherosclerosis. We assessed the long-term results of coronary artery bypass grafting performed during the past 13 years in 62 patients with heterozygous familial hypercholesterolemia, whose mean plasma total and low-density lipoprotein cholesterol level was 327 mg/dl and 238 mg/dl, respectively. The patients had severe coronary atherosclerosis, with coronary stenosis index of 19.7, and the prevalence of extracoronary atherosclerotic lesions was 27%. Sixty-one patients underwent successful coronary artery bypass operation, with an average of 2.5 grafts, and the coronary stenosis index decreased to 7.1. After operation, all patients consumed a cholesterol-lowering diet and received drug therapy with pravastatin, probucol, or cholestyramine. Seven patients who were resistant to drug therapy were treated with plasma low-density lipoprotein apheresis. The cholesterol-lowering therapy reduced plasma total cholesterol level by 37%, low-density lipoprotein cholesterol level by 42%, and low-density lipoprotein/high-density lipoprotein cholesterol ratio by 37% ( p < 0.001). During the follow-up period (mean, 52 months; range, 10 to 157 months), there was no cardiac death, but three patients died of malignant disease. The actuarial survival rate was 95% at 5 years and 89% at 12 years after operation. The actuarial freedom from recurrent angina was 90% at 5 years and 53% at 11 years after operation. Four patients underwent reoperation, an average of 8 years postoperatively, because of vein graft atherosclerosis. In spite of severe coronary atherosclerosis, these patients with familial hypercholesterolemia showed good long-term outcome after coronary artery bypass operation. The present findings suggest that aggressive use of arterial grafts, intensive cholesterol-lowering drug therapy, and low-density lipoprotein apheresis may be useful in patients with familial hypercholesterolemia. (J THORAC CARDIOVASC SURG 1995;109:364-9)

A 72-year-old woman who had been diagnosed as homozygous familial hypercholesterolemia was admitted for chest discomfort. Computed tomography and cardiac catheterization revealed severe calcification of the aortic root and a high grade stenosis of the proximal right coronary artery. Aortic valve replacement concomitant with coronary artery bypass was done using temporary hypothermic circulatory arrest. This is preferred method when dealing the calcified aorta.